87

Climbing Hills

Figure 7 shows the concept of climbing a hill , and the forces acting on

the three wheeler as a result .

The weight forces remain constant , but they

act in a line closer to the point of support A .

The inertia forces F depend on the acceleration . In units of " g " ,

standard acceleration of gravity , and for different hill slopes , the chart at

the bottom summarizes the results . To appreciate the fact that the

acceleration values are modest , an acceleration of 0 . 3g corresponds to about

10 feet / second / second . This is equivalent to attaining a speed of about 20

mph in 3 seconds , after traveling a distance of about 45 feet . ( It is , of

course , not necessary to travel the 45 feet ; it is sufficient to attain the

requisite acceleration ) .

Other Problems

I believe that the foregoing is sufficiently illustrative of the

possibilities . A complete analysis would include such matters as frame

deformation , the possibility of resonance in the system , and other items . As a

matter of interest , the Mckinley case involved a combination of riding on a

side slope and a sudden change in terrain requiring a turn .